Drill bit

ABSTRACT

A rotary drill bit having a plurality of journal-mounted rotating cutters, jet passageways through which drilling fluid is discharged between the cutters and check valves disposed in the passageways to permit drilling fluid to flow therethrough to the cutters and to prevent flow in reverse direction therethrough into the interior of the bit.

United States Patent Hollingshead [s41 DRILL BIT [72] Inventor: Frank A. Hollingshead, Houston,-

Tex.

[73] Assignee: G. W. Murphy Industries, Inc.,

Houston, Tex.

[22] Filed: March 1, 1971 [21] Appl. No.: 119,509

[52] US. Cl ..175/318, 175/340 7 [51] Int. Cl. ..E2lb 41/00 [58] Field of Search ..175/317, 318, 235, 337, 339,

[56] References Cited UNITED STATES PATENTS 2,293,259 8/1942 Johnson ..l75/340 X [151 3,685,601 1 Aug. 22, 1972 2,855,182 10/1958 Payne ..175/340 3,089,551 5/1963 Greene ..175/3 18 3,213,949 10/1965 Kistler ..175/317 X 3,401,758 9/1968 Talbert 175/337 X Primary Examiner-David H. Brown Attorney-J. Vincent Martin, Joe E. Edwards and Jack R. Springgate [57] ABSTRACT A rotary drill bit having a plurality of joumal-mounted rotating cutters, jet passageways through which drilling fluid is discharged between the cutters and check valves disposed in the passageways to permit drilling fluid to flow therethrough to the cutters and to prevent flow in reverse direction therethrough into the interior of the bit.

5 Claim, 4 Drawing Figures DRILL BIT BACKGROUND OF THE INVENTION The placement of one or more passageways in a rotary drilling bit to conduct air or other drilling fluids from the central bore of the bit to the rotating cutters is well known. The drilling fluid thus directed serves to cool the cutters and to carry cuttings away from the cutters. However, the presence of these passageways makes it possible for cuttings and other foreign materials to enter the interior of the bit when the circulation of the drilling fluid ceases and thus to impair the further operation of the bit. This problem has been dealt with by placing check valves or filters in the interior bore and passageways of rotary drill bits. For example, U.S. Pat. No. 3,198,269 to Nickles discloses a single passageway leading from the interior bore of the bit to the space directly above the rotary cutters. A springloaded check valve is placed in the interior bore and in the single passageway and serves as a nozzle to direct drilling fluid between the cutters and also serves to prevent reverse flow through the passageway into the interior bore. The check valve is removable through the top of the bit when it is disconnected from the .drill string.

However, the check valve assembly in the bit disclosed in the Nickles patent is removable from the bit only through the top thereof, thus necessitating the detachment of the bit from the drill string in orderto remove the check vaLve assembly. Further, the Nickles bit provides for only one passageway to direct drilling fluid between the bits and thus does not permit the application of a stream of drilling fluid at multiple points on the cutters. Further, the installment of the Nickles check valve assembly involves considerable retooling of a standard rotary bit.

SUMMARY OF THE INVENTION This invention relates to an improved design for rotary drill bits. The invention provides for a drill bit having a body with a plurality of arms extending therefrom, each arm having a pintle for supporting a rotary cutter mounted thereon. The body defines a central recess; a plurality of cooling passageways extend through the body from the central recess to the pintles and a plurality of jet passageways extend through the body from the central recess to discharge air between adjacent cutters. Flow control means, such as check valves, are placed in each of these jet passageways so that flow of the drilling fluid from the central recess and between the cutters is allowed, but flow from outside the body of the bit, through the jet passageways, and into the central recess is prevented. Thus, the detrimental introduction of foreign matter into the jet passageways, the central recess, the cooling passageways and other areas of the bit is prevented. Further, the flow control means also serves as a nozzle to direct flow between the cutters as desired.

An object of the present invention is to provide a rotary drill bit with multiple passageways extending through the body of the bit to facilitate the direction of multiple streams of drilling fluid onto the cutters as desired and prevent reverse flow therethrough.

Another object of this invention is to provide a rotary drill bit with means for excluding foreign matter from .the interior of the bit, where such bit may be easily and conveniently formed by adding the means for excluding the foreign matter to a conventional rotary drill bit without substantially retooling or other wise modifying the conventional bit.

Another object of this invention is to provide a rotary drill bit with means for excluding foreign matter from the interior of the bit, where such means are interchangeable with the standard nozzle bushing in the passageways between the interior bore of the bit and the exterior of the bit.

Another object of this invention is to provide a rotary drill bit with means for excluding foreign matter from the interior of the bit, where such means are of a reliable, noncomplex design with few moving parts.

Another object of this invention is to provide a rotary drill bit with means for excluding foreign matter from the interior of the bit, where such means are secured in the bit in a manner that permits easy access thereto for servicing and replacement thereof when desired, said access being available from the exterior of the bit without the need for detaching the bit from the drill string.

Other objects will be apparent from the drawings, the specification and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like reference numerals indicate like parts, and wherein illustrative embodiments of this invention are shown:

FIG. 1 is a view partly in elevation and partly in section showing a rotary drill bit embodying the present invention;

FIG. 2 is a vertical cross-sectional view taken along line 22 in FIG. 1;

FIG. 3 is a view partly in elevation and partly in section showing'the details of a spring-loaded check valve to be secured in the jet passageways of the drill bit in accordance with this invention; and

FIG. 4 is a horizontal cross-sectional view taken along line 4-4 in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 discloses the principal features of a rotary drill bit embodying the present invention. The body 10 of said bit defines a centrally located recess 11 and has three arms 12 depending therefrom, each arm having a pintle 13 with a rotary cutter 14 supported thereon in the'usual manner with the aid of ball bearings 15a and roller bearings 15b. A thread T permits the attachment of the bit to a drilling string (not shown).

Cooling passageways 16 extend through the body 10 from the central recess 11 to the recesses between the pintles and cutters, whereby relatively cool air may be introduced therebetween to cool the pintles and cutters after they become heated in the drilling operation.

Jet passageways 17 extend through the body 10 from the central recess 11 and are arranged to discharge air between the exterior surfaces of the cutters 15, whereby cuttings and other foreign matter are carried away from the cutters.

A spring-loaded, pivoting check valve nozzle 18 is secured in the lower portion of each jet passageway 17 by suitable means such as a set screw 19. The check valve nozzles 18 prevent the introduction of cuttings and other damaging foreign matter into the central recess 11, the cooling passageways 16, the area between the pintles and cutters, and other interior parts of the bit when the air flow therethrough is discontinued discontinued.

The details of the check valve nozzle 18 may be seen in FIGS. 3 and 4. The valve nozzle consists of a cylindrical hollow body 20, open at both ends. A pin 21 is secured across the interior of the valve nozzle with the pins axis perpendicular to the longitudinal axis of the body 20. A disc-shaped door or plate 22 is mounted on the pin 21 and us urged by a spring 23 into closing position against an annular shoulder 24 on the interior of the cylindrical body 20. The door 22 is beveled and has a diameter such that when shut it effectively prevents the passage of cuttings and other foreign matter through the valve. The open position of door 22 is shown in dashed lines in F IG. 4.

A check valve nozzle 18 is secured in each jet passageway 17 with shoulders 24 facing outwardly so that the pressure of the air from the central recess 11 will overcome the tension of the spring 23 and open the door 22 whereby the air is directed between the cutters.

The diameter and thickness of the valve nozzle body 20 are chosen so that the valve nozzle will fit snugly in the passageway 17 and so that the valve nozzle serves as an effective nozzle to direct the air stream between the exterior surfaces of the cutters as desired.

The valve nozzles 18 are interchangeable with standard nozzle bushings that are often disposed in the passageways 17 of standard rotary drill bits and the valve nozzles 18 may be removed from passageways 17 without detaching the bit from the drill string and going through the interior bore 1 1.

In operation, air or other drilling fluid is conducted under pressure through the drilling string (not shown) into the central recess 11, through the passageway 16 into the spaces between the pintles 13 and cutters 14, through the passageways l7 and valve nozzles 18 into the spaces between the exterior surfaces of the cutters. As explained, during normal drilling the air pressure overcomes the tension of springs 23 and the doors 22 pivot about pins 21 to permit air flow through the valve nozzles 18. When the air pressure is reduced, the doors 22 close securely against shoulders 24 to exclude foreign materials from the interior of the bit.

It will be appreciated that such valve nozzles can easily be secured in the jet passageways of many standard rotary drill bits without substantially modifying said drill bits and that these valve nozzles may be serviced or replaced as necessary with great ease and efficiency. Further, it is apparent that the design of these check valve nozzles affords a minimum opportunity for failure and that placing the valve nozzles according to this invention will enable them to direct the air between the exterior surfaces of the cutters as desired and to exclude the entry of foreign matter into the interior recesses and passageways of the bit.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

iyl fl lr comprising a body,

a plurality of rotary cutters,

means for rotatively mounting said cutters on said body,

said body defining a plurality of passageways, and

means in each of said passageways for directing flow outward from said bit between said cutters and for preventing reverse flow through said passageways.

2. The rotary bit of claim 1, wherein each of said flow control means is removable from and insertable into said passageway or passageways from the exterior of said bit body adjacent to said cutter or cutters and including means for releasably securing each of said control means in said passageway.

3. The rotary bit of claim 2, wherein each of said flow control means includes a check valve nozzle removably secured in each of said passageways and operable to permit fluid to flow through each of said passageways out of said bit body.

4. The rotary bit of claim 3 wherein each of said check valve nozzles includes a pivoting plate adapted to close said passageway, and

a spring urging said plate toward its closed position.

5. The rotary bit of claim 4 wherein said releasable means a set screw to removably secure each of said check valve nozzles in its passageway. 

1. A rotary drill bit, comprising a body, a plurality of rotary cutters, means for rotatively mounting said cutters on said body, said body defining a plurality of passageways, and means in each of said passageways for directing flow outward from said bit between said cutters and for preventing reverse flow through said passageways.
 2. The rotary bit of claim 1, wherein each of said flow control means is removable from and insertable into said passageway or passageways from the exterior of said bit body adjacent to said cutter or cutters and including means for releasably securing each of said control means in said passageway.
 3. The rotary bit of claim 2, wherein each of said flow control means includes a check valve nozzle removably secured in each of said passageways and operable to permit fluid to flow through each of said passageways out of said bit body.
 4. The rotary bit of claim 3 wherein each of said check valve nozzles includes a pivoting plate adapted to close said passageway, and a spring urging said plate toward its closed position.
 5. The rotary bit of claim 4 wherein said releasable means a set screw to removably secure each of said check valve nozzles in its passageway. 